The difference between PHP value passing and reference passing

Value passing (Sample demo)

1<?PHP2 //value passing: Within the scope of the function, changing the value of a variable is not likely to affect the values of the variables outside the function.3 functionTest$i){4     $i++;//variable i self-increment plus 15     $a=$i;//variable I assigns a value to the variable a6     return $a;//return variable a7 }8 9 $i= 5;//Define variable iTen Echo $i.‘ <br> ';//Output: 5 One EchoTest$i).‘ <br> ';//Output: 6 A Echo $i;//Output: 5

Reference Delivery (Sample demo)

1<?PHP2 //reference passing: Within the scope of the function, any change to the value is also reflected outside the function, because the pass-through reference is a memory address.3 functionTest (&$i){4     $i++;//variable i self-increment plus 15     $a=$i;//the reference to the variable i is passed to the variable a6     return $a;//return variable a7 }8 9 $i= 5;//Define variable iTen Echo $i.‘ <br> ';//Output: 5 One EchoTest$i).‘ <br> ';//Output: 6 A Echo $i;//Output: 6

Application Scenarios:

(1) When the value is passed, PHP must copy the value.

(2) Reference passing does not require copying values, so reference passing is generally used for large strings or objects.

Advantages and Disadvantages

(1) Passing values can be time consuming, especially for large strings and objects, which can be a costly operation.

(2) Transfer reference, any operation within the function is equivalent to the operation of the transfer variables, the transfer of large variables of high efficiency.

The difference between PHP value passing and reference passing